This invention relates to a dental articulator which can reproduce the positions of the mandibular condyles of a patient suffering from malocclusion and thus makes it possible for a dentist to treat the malocclusion by referring to the positions of the mandibular condyles reproduced on the articulator.
Articulators, which are used to manufacture dentures, are available in many types. One such articulator is called an arcon type mean value articulator, which comprises a lower jaw member, and two pillars each extending vertically upwardly from either side of the rear portion of the lower jaw member. The pillars each carry a ball, which corresponds to a mandibular condyle, at the top end thereof. An upper jaw member is disposed over the lower jaw member and carries housings each provided on either side of the rear portion thereof. Each of the balls is received in one of the housings so that the upper jaw member is vertically pivotable about the balls. In some of such articulators, the height of the balls are adjustable, and the upper and lower jaw members are movable back and forth relative to each other.
Such an articulator further includes a lower mounting disk mounted on the lower jaw member for mounting a lower jaw model, and an upper mounting disk mounted on the upper jaw member for mounting an upper jaw model. Such an articulator was originally developed to reproduce the movement of human jaws, more specifically the movement of the mandibular condyles by pivoting the upper jaw member until the teeth of the upper jaw model abuts the teeth of the lower jaw mode, thereby treating any malocclusion (see JP patent publication 2000-42004).
The term “centric occlusion” refers to the optimum position of the mandibular condyles. The term “habitual occlusion” refers to the position of the mandibular condyles when the opposed teeth of the upper and lower jaws are all stably in contact with each other.
If the centric occlusion and the habitual occlusion do not coincide, temporomandibular joint syndrome may result.
Many diagnostic techniques are known for checking if the centric occlusion and the habitual occlusion coincide. The most recent technique is to check if the mandibular condyles are in their optimal positions when the opposed teeth of the upper and lower jaws are all stably in contact with each other. For this purpose, three-dimensional X-rays and MRI are typically used.
But with this technique, it is impossible to measure the distance between the optimum positions of the mandibular condyles and their positions at the habitual occlusion.
A dentist uses such a dental articulator in preparing prostheses and also to treat temporomandibular joint syndrome.
But even though the optimal positions of the mandibular condyles are known, as long as this information cannot be reproduced on the articulator, it is impossible to use this information for the treatment of temporomandibular joint syndrome.
Some dental articulators have their balls as the mandibular condyles arranged to be vertically movable and their upper and lower jaw models movable back and forth relative to each other. In this arrangement, since the balls, which correspond to the mandibular condyles, vertically move, even though their optimum positions are known, such data cannot be reproduced on the articulator. Thus, it is impossible to diagnose and/or treat temporomandibular joint syndrome.
An object of the invention is to provide a dental articulator which can reproduce data on the optimum positions of mandibular condyles of a patient, whereby temporomandibular joint syndrome can be diagnosed or treated based on such data.